This practice set contains high-yield board review questions covering key concepts in Knee Sports. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.
Question 481
Topic: Knee Sports
A 38-year-old female presents with early medial compartment osteoarthritis, genu varum, and chronic anterior cruciate ligament (ACL) deficiency. When performing a high tibial osteotomy, how should the surgeon manage the posterior tibial slope to optimize sagittal stability?
Correct Answer & Explanation
. Decrease the posterior slope
Explanation
Decreasing the posterior tibial slope reduces the anterior translation of the tibia relative to the femur during weight-bearing. This altered biomechanics is protective for an ACL-deficient knee.
Question 482
Topic: Knee Sports
A 45-year-old patient presents with a 15-degree lower extremity varus deformity. Deformity analysis reveals the mLDFA is 102 degrees and the mPTA is 87 degrees. The surgeon plans an isolated high tibial osteotomy (HTO) to completely correct the mechanical axis deviation. What is the primary biomechanical complication of this approach?
Correct Answer & Explanation
. Excessive joint line obliquity causing shear stress
Explanation
Correcting a purely femoral deformity (abnormal mLDFA) with a tibial osteotomy will result in an excessively oblique joint line (medial down/lateral up). This creates detrimental shear forces across the articular cartilage and alters knee kinematics.
Question 483
Topic: Knee Sports
A patient with severe medial compartment osteoarthritis demonstrates a prominent lateral varus thrust during the stance phase of gait. This dynamic, multi-planar deformity is most directly exacerbated by the chronic stretching and loss of tension in which of the following structures?
Correct Answer & Explanation
. Lateral collateral ligament
Explanation
A varus thrust is characterized by dynamic lateral opening of the joint during stance. This is primarily permitted and exacerbated by incompetence or chronic stretching of the lateral collateral ligament (LCL) and posterolateral corner structures.
Question 484
Topic: Knee Sports
A 42-year-old female undergoes a standard medial opening wedge high tibial osteotomy (MOWHTO) proximal to the tibial tubercle for varus malalignment. Postoperatively, she develops new-onset anterior knee pain. Which of the following iatrogenic radiographic findings is the most likely cause?
Correct Answer & Explanation
. Patella infera (baja)
Explanation
A supratubercle MOWHTO elevates the proximal joint surface while leaving the tibial tubercle distal, effectively shortening the distance between the joint line and the tubercle. This functionally lowers the patella, creating patella infera (baja) and increasing retropatellar contact pressures.
Question 485
Topic: Knee Sports
A 58-year-old male presents with a long-standing, progressive genu varum deformity. Clinically, he exhibits a noticeable varus thrust during the stance phase of gait. Radiographs confirm severe medial compartment collapse. Which of the following statements best describes the soft tissue changes occurring on the lateral side of the knee in this progressive varus cascade?
Correct Answer & Explanation
. C. The lateral soft tissue structures, including the LCL, IT band, and PLC, are subjected to chronic tensile overload, leading to structural attenuation and lateral ligamentous laxity.
Explanation
Correct Answer: CThe case content describes the 'Varus Knee Cascade' and the 'Soft Tissue Envelope Under Duress.' It states that in progressive genu varum, while the medial side collapses due to massive compressive overload, the lateral soft tissue structures—including the lateral collateral ligament (LCL), the iliotibial (IT) band, and the complex posterolateral corner (PLC)—are subjected to chronic, repetitive tensile overload. This constant stretching leads to structural attenuation and profound functional lateral ligamentous laxity. This laxity, combined with medial collapse, allows for joint gapping and eventually lateral tibial subluxation, manifesting as a varus thrust.Option A is incorrectbecause the lateral structures are stretched and become lax, not shortened or contracted. Shortening would occur on the concave (medial) side in severe, chronic cases, but the primary issue on the lateral side is stretching.Option B is incorrectbecause the IT band is subjected to tensile overload and stretching, not hypertonicity that increases lateral compartment compression. The lateral compartment is typically unloaded in varus.Option D is incorrectbecause while lateral meniscus extrusion can occur, the primary soft tissue response described for the ligaments and IT band is stretching and laxity, not compensatory tightening of the capsule.Option E is incorrectbecause the case explicitly details how the soft tissue envelope is profoundly affected, with lateral structures becoming lax, which is a critical component of the progressive varus collapse and dynamic instability.
Question 486
Topic: Knee Sports
A 60-year-old male presents with progressive right knee pain. A standing long-leg alignment radiograph reveals a mechanical axis that passes 15mm medial to the center of the knee joint. Which of the following best describes this patient's alignment and its biomechanical implication?
Correct Answer & Explanation
. Varus malalignment, leading to medial compartment overload.
Explanation
Correct Answer: CThe Mechanical Axis Deviation (MAD) is a critical metric for assessing global limb alignment. The text states that in a perfectly aligned limb, the MAD passes near the center of the knee joint (1 to 8 mm medial to the tibial spine). If the mechanical axis falls medial to the center of the knee, it indicates a varus malalignment. This creates a destructive bending moment that overloads the medial compartment, leading to medial meniscus tearing, articular cartilage degradation, and eventual medial compartment osteoarthritis. Therefore, a MAD passing 15mm medial to the knee center signifies varus malalignment and medial compartment overload.Options A, D, and E are incorrect because they either misidentify the type of malalignment (valgus) or misstate the compartment overloaded. Option B is incorrect as 15mm medial is outside the normal range for neutral alignment.
Question 487
Topic: Knee Sports
A 38-year-old male presents with chronic knee pain and a noticeable limp following a malunited distal femoral fracture 5 years prior. Full-length weight-bearing radiographs reveal a mechanical axis deviation (MAD) of 25 mm medial to the center of the knee. Which of the following best describes the biomechanical consequence of this finding?
Correct Answer & Explanation
. B. Pathological overloading of the medial compartment of the knee, leading to accelerated medial compartment osteoarthritis.
Explanation
Correct Answer: BThe case explicitly states that a medial MAD (varus deformity) causes the mechanical axis to shift medially, pathologically overloading the medial compartment of the knee. This leads to medial meniscus tearing, subchondral sclerosis, and rapid-onset premature medial compartment osteoarthritis. A 25 mm medial MAD is a significant deviation, indicating severe varus malalignment.Option A is incorrectbecause increased tensile stress on the LCL and lateral compartment overload are characteristic of a lateral MAD (valgus deformity), not a medial MAD.Option C is incorrectbecause while an HTO might be considered for varus, the deformity is explicitly stated to be a malunited distal femoral fracture. Therefore, the primary source of the deformity is femoral, and a distal femoral osteotomy (DFO) would likely be indicated, not an HTO, without further assessment of joint orientation angles to pinpoint the exact source.Option D is incorrectbecause a normal MAD is zero, with the mechanical axis passing directly through the center of the knee or slightly medial to the tibial spines. A 25 mm medial deviation is highly pathological and not a normal variant.Option E is incorrectbecause while limb malalignment can affect patellofemoral mechanics, a medial MAD primarily impacts the tibiofemoral compartments, leading to medial compartment overload, rather than directly increasing the risk of patellofemoral instability, which is more commonly associated with valgus alignment or specific patellofemoral pathologies.
Question 488
Topic: Knee Sports
A 55-year-old patient presents with a significant varus deformity of the knee, as depicted in the full-length standing radiograph below. The text highlights the biomechanical consequences of such a deformity if left uncorrected. What is the most likely long-term consequence of this uncorrected varus deformity on the knee joint?
Correct Answer & Explanation
. B. Accelerated medial compartment arthrosis.
Explanation
Correct Answer: BThe text explicitly states: 'In a varus knee, the medial compartment bears a disproportionate amount of the load, leading to accelerated medial compartment arthrosis.' The image clearly shows a varus deformity, where the mechanical axis passes medial to the center of the knee, thus overloading the medial compartment.Incorrect Options:A. Accelerated lateral compartment arthrosis:This is the consequence of a valgus deformity, where the lateral compartment is overloaded, not a varus deformity.C. Development of genu valgum in the contralateral limb:While compensatory mechanisms can occur, the text does not describe this as a direct biomechanical consequence of an uncorrected varus deformity in the ipsilateral knee.D. Increased risk of patellar instability:Patellar instability is typically associated with factors like trochlear dysplasia, patella alta, or excessive tibial tuberosity-trochlear groove distance, not primarily with frontal plane varus deformity of the knee.E. Improved range of motion due to joint laxity:Uncorrected deformity and subsequent arthrosis typically lead to decreased and painful range of motion, not improved range of motion.
Question 489
Topic: Knee Sports
A patient presents with a severe long-standing varus deformity of the tibia and a compensatory valgus deformity of the femur. If the surgeon only corrects the tibial varus deformity to mechanical neutrality without addressing the femur, what will be the likely effect on the knee joint?
Correct Answer & Explanation
. The joint line will become unacceptably oblique (loss of joint line congruity with the ground).
Explanation
Correcting only one component of a compensatory dual-bone deformity shifts the mechanical axis but often creates an abnormally oblique joint line. A level knee joint line is critical for mitigating shear forces during weight-bearing.
Question 490
Topic: Knee Sports
A 70-year-old female presents with severe bilateral knee osteoarthritis, with the right knee exhibiting a significant valgus deformity and the left knee a varus deformity. The image below shows the left lower extremity. For the left knee, the mechanical axis line passes significantly medial to the center of the knee. Which of the following statements accurately describes the biomechanical consequence of this specific alignment?
Correct Answer & Explanation
. It results in accelerated articular cartilage wear in the medial compartment.
Explanation
Correct Answer: DThe image and description indicate a varus malalignment (bow-legged deformity) where the mechanical axis line passes significantly medial to the center of the knee. The case explicitly states that 'Varus Malalignment... results in severe overloading of the medial compartment of the knee, leading to accelerated articular cartilage wear, medial meniscus tearing, and early-onset osteoarthritis.' Therefore, accelerated articular cartilage wear in the medial compartment is a direct biomechanical consequence.Options A, B, and C are incorrectbecause these are biomechanical consequences typically associated with a valgus malalignment (knock-kneed deformity), where the mechanical axis passes lateral to the center of the knee, overloading the lateral compartment, stretching the MCL, and compressing the lateral meniscus.Option E is incorrectbecause the description 'mechanical axis line passes significantly medial to the center of the knee' and the 'bow-legged' appearance are characteristic of varus malalignment, not valgus.
Question 491
Topic: Knee Sports
When utilizing a Taylor Spatial Frame for a complex six-axis deformity correction of the tibia, which of the following is an essential parameter required by the software to accurately calculate the daily strut adjustments?
Correct Answer & Explanation
. Mounting parameters
Explanation
The TSF software requires precise input of deformity parameters, frame parameters, and mounting parameters (the exact position of the reference ring relative to the bone) to accurately generate the correction schedule.
Question 492
Topic: Knee Sports
Figures A and B show routine postoperative radiographs obtained 2 weeks after anterior cruciate ligament (ACL) reconstruction with autologous patellar tendon graft. Based on these findings, what is the next most appropriate action? Review Topic
Correct Answer & Explanation
. Revision ACL surgery
Explanation
The radiographs reveal an intra-articular position of the femoral bone plug; therefore, revision ACL surgery is indicated. Recognized early, this graft may be suitable to use for the revision, but an alternate should be available.
Question 493
Topic: Knee Sports
Below show the radiographs and the MRIs obtained from a 40-year-old man with worsening left knee pain. A full hip-to-ankle radiograph shows a 5-degree varus knee deformity. The patient sustained a major left knee injury 5 years ago and a confirmed complete anterior cruciate ligament (ACL) tear. He managed this injury nonsurgically with a functional brace but experienced worsening pain. He was seen by an orthopaedic surgeon 18 months ago, and a medial meniscus tear was diagnosed; the tear was treated with an arthroscopic partial medial meniscectomy. Since then, his knee has been giving way more often, and he no longer feels safe working on a pitched roof. The patient received 6 months of formal physical therapy and was fitted for a new functional ACL brace, but he still has pain and instability. He believes he has exhausted his nonsurgical options and would like to undergo surgery. What is the most appropriate treatment at this time?
Correct Answer & Explanation
. Proximal tibial osteotomy with subsequent ACL reconstruction
Explanation
DISCUSSION: Proximal tibial osteotomy is the most appropriate intervention to correct varus malalignment and to reduce stress on the ACL. In some cases, proximal tibial osteotomy alone may address both pain and instability, but if instability persists, particularly in the setting in which instability can be dangerous, subsequent ACL reconstruction can further stabilize the knee with less stress on the graft after the correction of malalignment. Varus alignment places increased stress on the native or reconstructed ACL. ACL reconstruction should be performed only at the same time as or following proximal tibial osteotomy to correct alignment in the setting of varus malalignment. It is not appropriate to perform ACL reconstruction prior to proximal tibial osteotomy in this setting. Distal femoral osteotomy is not indicated to correct varus malalignment. Varus alignment places increased stress on the native or reconstructed ACL, and ACL reconstruction alone is not indicated for this patient.
Question 494
Topic: Knee Sports
After surgery, this patient continues to experience pain and swelling of the knee with recurrent effusions. He returns to the office with continued pain 2 years after surgery. He describes instability, particularly when descending stairs. Upon examination, there is range of motion from 0 to 120 degrees with no extensor lag. The knee is stable to varus and valgus stress in extension, but there is flexion instability in both the anterior-posterior direction and in the varus-valgus direction. Bracing leads to a slight decrease in symptoms but is not well tolerated. Isokinetic testing demonstrates decreased knee extension velocity at mid push. Radiographs demonstrate well-aligned and fixed knee implants. An infection workup is negative. What is the most appropriate surgical intervention at this time?
Correct Answer & Explanation
. Tibial polyethylene exchange
Explanation
DISCUSSIONVideo 99 for referenceThis patient has valgus knee alignment, and, after undergoing appropriate bone resections and soft-tissue balancing, has demonstrated a tight PCL on trial reduction as evidenced by lift-off of the trial insert as described by Scott and Chmell. The appropriate maneuver is PCL recession with partial release of tight (usually anterolateral) PCL fibers. However, for this patient, instability resulted in increased anterior translation. At this stage, the options are to convert to either a deeper-dish insert with increased sagittal conformity or a posterior stabilized insert. The only appropriate choice among the responses is use of an insert with increased sagittal conformity to prevent excessive anterior translation. Increasing the polyethylene could improve stability in flexion, but, considering there is good stability in extension, this likely would lead to an inability to achieve full extension. The patient’s valgus deformity, flexion contracture, correction with release of the iliotibial band, and posterolateral capsule predispose him to increased risk for peroneal nerve palsy. His symptoms at follow-up suggest knee flexioninstability with pain, swelling, and difficulty descending stairs. Considering his history, an incompetent PCL must be considered. Revision of the knee to a posterior stabilized or nonlinked constrained condylar implant depending on the condition of the ligaments likely is needed to address his symptoms. The difference in extension vs flexion stability makes polyethylene exchange a poor option. There is no reason to believe a constrained rotating hinge design is necessary. Repeat use of a PCL-retaining insert is not recommended.
Question 495
Topic: Knee Sports
An elite football player has sustained a left knee injury during play. A dynamic imaging analysis is performed on the affected knee, which shows anterior shift and internal rotation of the tibia at low flexion angles. There is also some mild medial translation of the tibia at greater flexion angles. What structure(s) have most likely been injury? Review Topic
Correct Answer & Explanation
. Anterior cruciate ligament
Explanation
This patient has sustained an anterior cruciate ligament (ACL) rupture.The ACL is the primary restraint to anterior translation of the tibia relative to the femur. It also acts as secondary restraint to tibial rotation and varus/valgus rotation. ACL-deficient knees have been shown to have abnormal knee kinematics, which has been thought to contribute to the osteoarthritis that develops after injury.DeFrate et al. examined the knee joint kinematics of 8 patients with unilateral anterior cruciate ligament rupture using in vivo imaging. They found significant anterior shift and internal rotation of the tibia at low flexion angles in ACL-deficient knees. They also noted some medial translation of the tibia between 15° and 90° of flexion.Illustration A shows the effect of medial tibial translation on tibiofemoral contact in ACL-deficient knees. The medial translation of the tibia causes increased contact between the tibial spine and inner surface of the medial femoral condyle. This might be a contributing factor to the joint degeneration observed in ACL-deficient patients.Incorrect Answers:
Question 496
Topic: Knee Sports
During a posterior cruciate ligament (PCL)-retaining total knee arthroplasty, a critical principle to remember is to
Correct Answer & Explanation
. accurately tension the PCL.
Explanation
Maintenance of the joint line and accurately tensioning the PCL are critical in the proper execution of a PCL-retaining total knee arthroplasty. Appropriate tension helps ensure femoral rollback and avoid stiffness or instability. Raising the joint line to help ensure full extension should be avoided in cruciate-retaining knees, because doing so creates an unfavorable kinematic environment. The three important principles of surgical technique needed to maintain appropriate tensioning of the PCL include 1) choosing the proper femur size to reproduce the native femoral anterior/posterior dimension, 2) reproducing the joint line by resecting as much tibia from the healthy side as will be replaced by the smallest thickness of the tibial component and, 3) ensuring that full extension is achieved by soft-tissue releases and not by taking additional distal femur, as may be done in a posterior stabilized approach. Another important principle is to re-create the natural degree of the patient’s posterior tibial slope to avoid tightness in flexion.
Question 497
Topic: Knee Sports
Performing reconstruction of the anterior cruciate ligament by drilling the femoral tunnel via an anteromedial portal, in contrast to transtibial drilling, affords what theoretical benefit? Review Topic
Correct Answer & Explanation
. Diminished risk to lateral femoral articular cartilage and subchondral bone posteriorly
Explanation
Recent trends in anterior cruciate ligament reconstruction include an emphasis on anatomic rather than isometric reconstruction of the ligament. According to some studies, this more effectively restores knee kinematics and with this, rotatory stability. Transtibial drilling affords limited access to the lateral intercondylar wall and has been associated with vertical graft orientation. The anteromedial portal, in contrast, allows independent femoral tunnel drilling and more anatomic positioning of the graft. A more anatomically positioned tunnel established via an anteromedial portal may afford increased tunnel and graft obliquity. This has been suggested to resolve rotatory instability. Knee flexion angle during the course of reaming has been studied to assess favorable and negative tunnel characteristics and hazards to regional anatomic structures. When compared with transtibial drilling, the anteromedial portal is associated with shorter femoral tunnels, posterior tunnel wall integrity compromise, and increased risk to lateral femoral articular cartilage and subchondral bone posteriorly.
Question 498
Topic: Knee Sports
A 19-year-old running back lands directly on his anterior knee after being tackled. He has mild anterior knee pain, a trace effusion, a 2+ posterior drawer, a grade 1+ stable Lachman, no valgus laxity, and negative dial tests at 30 degrees and 90 degrees. What is the best treatment strategy at this time? Review Topic
Correct Answer & Explanation
. Physical therapy with a focus on quadriceps strengthening
Explanation
This patient has likely sustained an isolated PCL injury. The examination is consistent with a grade II injury to the PCL. In this scenario, the best initial option is nonsurgical treatment and return to play as symptoms subside and strength improves. Physical therapy with a focus on quadriceps strengthening and delayed PCL reconstruction is not the answer because this patient can likely be treated without surgery. The absence of valgus laxity and negative dial testing findings suggest that an injury to the posteromedial and posterolateral corners has not occurred. Initial nonsurgical treatment is indicated for this patient. If he completes rehabilitation and experiences persistent disability with anterior and/or medial knee discomfort or senses the knee is "loose," PCL reconstruction should be considered at that time.
Question 499
Topic: Knee Sports
The blood supply to the anterior cruciate ligament is primarily derived from what artery?
Correct Answer & Explanation
. Middle geniculate
Explanation
Microvascular studies have shown that the majority of the blood supply to the cruciate ligaments comes from the middle geniculate artery, although there is collateral flow through the other geniculates and from bone.
Question 500
Topic: Knee Sports
An 18-year-old man underwent open reduction and internal fixation of a tibial spine avulsion and a posterolateral corner repair. Two years later, he underwent lateral collateral ligament (LCL) and posterolateral corner reconstruction because of instability. Examination reveals a pronounced lateral varus knee thrust when ambulating. Varus stress in 30 degrees of flexion produces a 10-mm opening that is eliminated in extension. The Lachman test is 2 mm with a firm end point, and the posterior drawer test is negative. Standing radiographs show widening of the lateral joint space and a 5-degree mechanical varus alignment. What is the most effective course of treatment?
Correct Answer & Explanation
. Valgus-producing high tibial osteotomy (HTO)
Explanation
The patient has chronic posterolateral instability with a varus knee alignment; therefore, the most effective treatment is a valgus-producing HTO. A repeat soft-tissue reconstruction without correction of the varus alignment will most likely fail. An ACL reconstruction is not indicated with a normal Lachman test. Physical therapy and bracing will have little effect.
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